(Not Applicable)
(Not Applicable)
The present invention relates to a towed/surrogate decoy transmitter connected via a tow cable to a platform or host aircraft and in communication using a wireless communicator link, the wireless link providing useful performance and status information of the decoy transmitter to the host aircraft. The tow cable provides a mechanical connection to the host aircraft as well as a prime power connection and in some cases, a fiber optic (FO) interface. In order to optimize the protection provided by the towed/surrogate decoy transmitter, the host aircraft will use the wireless communication link to transmit operational status and control adjustment data back to the towed/surrogate decoy transmitter. The towed/surrogate decoy transmitter utilizes a wireless communicator link that can transmit data to any cooperative host aircraft and any other cooperative towed/surrogate decoy transmitters.
Military aircraft operating in hostile airspace require protection against radio frequency (RF) based tracking missiles. One method of providing the needed protection is through the use of a towed/surrogate transmitter. This towed/surrogate transmitter may be dropped, fired, towed or otherwise deployed from the aircraft to be protected. The towed/surrogate transmitter acts as a decoy for the RF based tracking missile, resulting in the missile missing its target, the host aircraft, by a sufficient distance to result in survival of the host aircraft from the attack although the decoy may be sacrificed to save the aircraft.
It is important to ensure optimal performance of the decoy. However, without feedback on the operational status of the decoy, back to the host aircraft, the host aircraft is not warned of a failure and may not take the appropriate action to sever the decoy and deploy an operational replacement. Without any decoy operational status feedback, it is also difficult for several host aircraft to cooperate with one another for an optimal defense, where the transmitter assets of multiple aircraft can be shared to offer greater protection.
Towed/surrogate decoys presently communicate with the host aircraft in one of two ways. The first method is the use of fiber optic (FO) cable. For a two-way communication link using fiber optic cables, both the decoy and host aircraft must contain optical lasers and detectors. This method is expensive, because extensive modifications would be required in both the already existing decoy and host aircraft, and the complexity of a two-way link precludes it from being used in low cost, high volume decoy applications. For this reason, all current fiber optic towed decoys employ only a one-way fiber optic communications link from the host aircraft to the decoy, and optimization of the decoy operational performance is difficult. The FO interface between the host aircraft and the decoy is primarily used to relay the RF electronic countermeasure (ECM) information to the high power transmitter resident in the decoy. If the FO interface were to be used to relay decoy control information, the transmission of critical RF data, required to protect the aircraft from a missile attach, would be interrupted during the time that it takes to send the information to the decoy control circuitry.
The second method for a two-way communication link is through the use of a modem. The modem can be used in two ways. It can be used to superimpose the communication signals onto one of the prime power lines. This first modem realization requires that a modem and a means of coupling must be present on both the decoy and the host aircraft. The second modem realization requires that a modem must be present on both the decoy and host aircraft and a dedicated wire link must also be used. The wire link is typically at least two wires. This method is also expensive, because extensive modifications would be required in the already existing decoy, host aircraft, and the tow line (the adding of 2 wires). Some fiber optic towed decoys employ only a one-way modem communications link from either the host aircraft to the decoy, or from the decoy to the host aircraft. Lack of an easily implementable 2-way communication link to exchange operational status and control adjustment data between the decoy and host aircraft complicates the optimization of the ECM systems.
The decoy can also operate as a simple repeater. As a repeater, there is usually not any need for an aircraft communications interface. However, the optimization of decoy performance could benefit from such an interface.
An improved method of communications between a towed transmitter and the host aircraft to protect an aircraft against RF based tracking threats from a hostile source is disclosed. In order to deceive the RF based tracking radar, a towed/surrogate decoy transmitter is towed behind the platform or aircraft and the RF transmission is radiated by the decoy transmitter instead of the transmitters on board the aircraft. The RF based tracking missile will then lock on to the decoy transmitter instead of the aircraft. Depending on the type of tracking missile being defended against, the RF protection system can employ a variety of RF modulation schemes, called techniques, which prove effective against the particular threat. In order to be able to properly modulate the RF signal, the aircraft protection system needs to receive the operating status of the transmitter located in the towed decoy. This updated knowledge of the operating status will allow the protection system to optimize the transmitter RF drive signal from the aircraft or to command, via the control adjustment data, the decoy control circuitry to change.
In order to eliminate or minimize RF radiations/transmissions emanating from the host aircraft itself, the RF ECM signal, that is generated by the ECM system on-board the host aircraft, is transmitted by the towed/surrogate decoy transmitter. The signal generated by the host aircraft ECM system is transmitted through a FO cable within the tow line. Due to size and weight considerations of alternate means of transmission, fiber optics is normally used to transmit the RF signal to the towed/surrogate decoy transmitter. Due to size and cost constraints, associated with high quality lasers and detectors, the fiber optic path is typically a one-way communication link only from the host aircraft to the decoy. The only methods for the aircraft to monitor the RF transmission is to either receive the signal itself or be able to monitor transmitted signals through the use of detectors on the decoy. However, even if the host aircraft could monitor the RF transmission of the decoy using detectors on the decoy, there is no communication link, from the host aircraft to the decoy, to permit any operational parameters of the decoy transmitter to be adjusted.
It is important to ensure optimal performance of the decoy. However, without feedback on the status of the decoy back to the host aircraft, the host aircraft may not detect a failure or non-optimal operating performance in time to take appropriate action, from a simple parameter adjustment to severing the decoy and deploying a replacement.
The present invention has added a two-way RF communication link, for the purpose of sharing decoy status and operational performance of the decoy with the host aircraft. The transceivers of the two-way RF communication link can be separate circuits from the decoy transmitter circuitry. Using present cellular technology, the cost and miniaturization of the circuitry has already been achieved. The other advantage of separate circuitry, including radiating apertures/antennas, is that the operational parameters can be modified, while the towed/surrogate decoy transmitter is transmitting its RF ECM transmission to the RF based tracking radar/missile. However, it is also possible to inject the RF communication signals into the high power transmission path and utilize the existing transmitter assets and radiating aperture.
This communication link is used to monitor and potentially adjust the operational parameters of the towed/surrogate decoy transmitter. Built-In-Test (BIT) circuitry is utilized in the towed/surrogate decoy transmitter to monitor the operational parameters. As an example, power detectors that measure the radiated RF output power can be included in the radiating apertures of the transmitter. If the BIT circuitry on-board the decoy indicates that the decoy is not functioning properly, the host aircraft could be warned of the failure and appropriate action can be taken. The action taken may be to send operational adjust data to correct the operational performance or to sever the decoy and deploy an operational replacement.
In order to correct the operational performance, operational control circuitry in the decoy will process the operational adjust data from the host aircraft. The BIT circuit will monitor the modified performance and send this data to the transceivers for communication with the host aircraft.
If the towed/surrogate decoy transmitter is a simple repeater without a FO communication link to the host aircraft, the host aircraft could still receive the signal transmitted from the decoy and provide operational adjust data for the decoy operational control circuitry to process.
The host aircraft contains a host RF wireless transceiver to link with the decoy RF wireless transceiver. The performance information received by the host RF wireless transceiver is passed to the host aircraft operational control circuitry. This electronic circuitry on-board the host aircraft can process the performance data from the decoy, take appropriate corrective actions (i.e. sending control adjustment data, or severing the decoy and deploying another decoy). This information is transmitted from the host RF wireless transceiver for communication with the decoy RF wireless transceiver. For the purpose of optimizing the RF ECM signal effectiveness, the host aircraft operational control circuitry can adjust the RF input signal driving the towed decoy transmitter or any necessary adjustment, including, but not limited to modulation or signal strength. This RF input signal is transmitted through the FO tow line to the towed/surrogate decoy transmitter, where the signal is amplified for RF transmission.
The RF wireless communication signals can be transmitted to other aircraft, or towed/surrogate decoy transmitters for an optimized cooperative protection strategy.